Postby cmma01 » Sat Jan 31, 2009 1:31 pm

I have recently been at a medical equipment auction and bought an old audiometric testing booth to give me a small soundproofed area for recording. It has a power supply to operate the electrics - silent ventilation fan and a light. It has a 3-core cable with the plug cut off.

The wire colours are unusual so I thought it best to check where to put what before I wire a new plug.

It's a thickish cable (approx 1 cm) so I have put a 13 amp fuse in the plug. The 3 wires within the cable are coloured black, green and very,very pale beige. I am guessing that green is live, black is neutral and the pale beige is earth but could be so very wrong!

So can someone tell me which is live, which neutral and which earth.

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Postby SparkyPaul » Sat Jan 31, 2009 5:54 pm

You need an electrician to check what you are doing - dont do anything till they have had a look
those colours sound like they are american but i'm not 100% certain
they use green for earth
black for hot
white for neutral
but like I said get an electrician to take a look first
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Postby sparx » Sat Jan 31, 2009 9:18 pm

Green will not be live no matter what!
My initial reaction was bk=Neutral, Green = earth, pale beige could be faded red = live BUT I believe what you have is a low voltage , possibly DC installation which should have a power supply with it.
A smallish fan and a light would not need a very big flex unless running at low voltage.
See if you can find a rating plate on fan or light, before risking burning out the lot!
regards SPARX
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Postby cmma01 » Sat Jan 31, 2009 10:22 pm

Fear not - no need to stop. I haven't started! Like I said, I did realise I could be so very wrong so I'm glad I asked. Thanks for your reply sparx.

The beige doesn't look like a faded red. I cut a chunk off the cable to get to fresh unexposed wire and it's the same colour throughout.

Since posting, I had a thought. Although the booth comes from a UK distributor, the 'mother company' is possibly American so I did wonder if the cubicle might be an import. I 'googled' that idea and see that American wiring would mean the black wire would be live, the green wire the earth and the remaining wire (which should be white) would be neutral. It's possible that the very, very pale beige could be a discoloured white but it's hard to tell.

I can't find any rating plate anywhere but will have another look tomorrow in daylight.

Thanks for your reply.
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Postby cmma01 » Sun Feb 01, 2009 6:14 pm

No rating plate anywhere sparx. The light fitting inside has regular brown, blue and green/yellow UK wiring and the fan the same.
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Postby sparx » Tue Feb 03, 2009 9:23 pm

Can you remove the lamp/bulb to see if it has a voltage printed on it?
the reason for the heavy flex mains lead may just be for mechanical protection as people tend to walk on leads when the booths are placed in temp. locations.
If all else fails test between what seems like earth core of flex ,and any metal work on light/fan, if you get a low ohms reading or other signs of continuity put in a 3A fuse and see what happens when switched on/off quickly!
You can only wonder 'what if' for so long.....
good luck SPARX,
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Postby cmma01 » Fri Feb 06, 2009 10:51 am

I have spoken with the UK distributors of the booth and sent photos. They think it's one of their American booths but were confused by the American wiring of the flex and UK wiring in the internal light fitting, so said they were not sure if it would be a 110v or 240v set up.

The bulb in the strip light is stamped 'made in England' 30 watt and the wiring is brown, blue, green/yellow - so a thoroughly British unit there.

The fan was supplied by Pamotor in California, [u]but[/u] made in [b]WEST[/b] Germany, so clearly a pre-1990 model. It is a 20w fan, 50/60Hz, 220/230v with just 2 wires - black and yellow (what country is that from!)

My guess now is that this was a US model specifically imported and wired for the UK/European market except for not having a UK/European style external flex. As the fittings are all suited to UK voltage, I suspect that the American flex is a red herring and I should connect black to the live, the beige to the neutral and the green to the earth.

What do you think?

Didn't understand your earth test suggestion incidentally - wouldn't that require the cable to be connected to the power - not quite ready to do that yet.
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Postby cmma01 » Fri Feb 06, 2009 11:16 am

Further information, having removed the roof of the booth.

The flex, light fitting and fan are linked electrically with connectors, and the wires are joined thus:

(1) The green from the flex is screwed to the metal casing of the booth (earth)

(2) The beige from the flex, the yellow from the fan and the blue of the light are all joined together, so my assumption is that they are the neutral wires in the set.

(3) The black from the flex is linked with the brown of the light (live).

(4) The black from the fan is connected to the green/yellow from the light fitting (earth)

(5) The fan has no live wire connection it would appear.

If this all looks kosher to you sparx, then I'm feeling confident that I can just wire the flex up with the black in live, the beige in neutral and the green in earth.
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